Flash photography / Artificial lighting sources

Flash photography divides the photographic community just as much as the question as to how much digital post-processing is acceptable. A large number of the pro available light photographers criticise the changing of natural lighting conditions, the artificial feel of flash images and do not use a flash at all. Other photographers appreciate the flash that can be seen in the images and use it to effect. A flash can create an interesting, characteristic image effect. In addition, the beholder is reminded of the photographer’s presence in the images.

Another reason for the flash’s poor reputation has nothing to do with the image effect caused by the source of light but instead has to do with the fact that many people feel uncomfortable when a flash is used e.g. at party events a large amount of flash photography changes the atmosphere.

Fact is that using a flash is challenging even for professional photographers although the manufacturers would like to tell us otherwise. Often the flash doesn’t have the desired effect. Rash use of the flash can easily change the atmosphere.

The topic of flash photography is relatively complex and touches on many technical aspects of photography. For many beginners, the amount of aspects and their connections can be somewhat confusing and can be discouraging.

Although I own a number of high performance flashes, I usually left them at home when I was on my travels. The built-in flash (if provided) proved to be relatively good on the few occasions it was required. It was generally used as a fill flash in correlation with a slow synchronisation and a synchronisation of the second shutter curtain. This was done in order not to ruin the lighting mood. Read the article about slow synchronisation for more information.

Most modern digital cameras have a built-in flash. These flashes usually only provide inadequate performance (guide number +/-12). Additionally, there are further restrictions which make using other flashes a requirement.

A fill flash is usually used lightly as the available light should still be image effective. Often an untrained eye cannot see that a flash was used. The natural lighting mood should be captured whenever possible. The fill flash is often used depict a great subject contrast by brightening deep shadow areas (e.g. sunlight, to brighten under eye shadows).

A very good option that can be used to determine the lighting effects of flash photography is a separate flash. This entails positioning the flash separately from the camera itself. The problem of flat illumination due to a head on flash can successfully be avoided. Additionally, the red eye effect is reduced to a minimum.

In flash exposure, the flash’s illumination is determined by flash performance, diaphragm and ISO rate. For the flash sync speed, the exposure has no influence on the illumination caused by the flash because modern electronic flashes only emit light for a very brief period and the lengths of time are well within the camera’s exposure time. However, exposure time has an impact on the overall exposure.

The guide number is the product of the diaphragms f-number and the distance to subject for correct exposure. The number indicates the flash range and therefore the flash’s performance. In order to compare flash devices properly, the aspects mentioned below should be taken into consideration.

Light from a flash can influence the lighting mood very negatively. A classic example is a candle lit atmosphere. If a flash used in this type of situation, the whole mood can be shattered. Therefore you should not carelessly use a flash even if the lighting is too dark.

Generally cameras flashes use shutter speeds of ca. 1/250 to 1/30 seconds. These speeds depend mainly on the flash synchronisation speed of the camera. The basic idea behind it is that the flash along with the available light illuminates the subject to such an extent that a shutter speed that won't cause motion blurring and can be used without requiring use a tripod.

The synchronisation of the flash to the first or rear shutter curtain is noticeable when using slower shutter speeds and capturing moving subjects. This setting determines whether the camera flashes at the beginning of exposure period (first shutter curtain) or at the end of the exposure period (rear shutter curtain).

Another notorious problem that occurs in flash photography is the „red eye effect“. This problem mainly occurs with built-in flashes where the distance between flash reflector and lens is very short. What is the cause of this phenomenon?

A common problem with flash photography is a background that is too dark. The foreground has the correct exposure but the background has simply become a black mass. Especially when using a direct flash (in contrast to indirect flash, the flash is pointed directly at the subject) many photographers have to grapple with this problem. However, this is no camera defect but is instead contributed to basic principles of physics, the “law of quadric reciprocity”